[EnergyPlus_Support] increased sizing:parameter gives more hours not met - DX cooling

["Jean marais" <jeannieboef@xxxxxxxxx>]

Dear Group,
Normally, upping the sizing factor should decrease unmet loads. I'm experiencing the OPPOSITE effect. I'm wondering if the curves describing the DX performance are mucking me about. They are default curves from design builder. Should I be adjusting these for a ASHRAE baseline case model?

  Coil:Cooling:DX:SingleSpeed,
    118451 AHU Cooling Coil, !- Name
    SchCpct_LowTempClgOFF,                   !- Availability Schedule Name
    autosize,                !- Rated Total Cooling Capacity {W}
    autosize,                !- Rated Sensible Heat Ratio
    3.81,                    !- Rated COP
    autosize,                !- Rated Air Flow Rate {m3/s}
    ,                        !- Rated Evaporator Fan Power Per Volume Flow Rate {W/(m3/s)}
    118451 AHU Gas Heating Coil Outlet,  !- Air Inlet Node Name
    118451 Unitary Unit Outlet,  !- Air Outlet Node Name
    118451 AHU DX Coil Cap-FT,  !- Total Cooling Capacity Function of Temperature Curve Name
    118451 AHU DX Coil Cap-FF,  !- Total Cooling Capacity Function of Flow Fraction Curve Name
    118451 AHU DX Coil EIR-FT,  !- Energy Input Ratio Function of Temperature Curve Name
    118451 AHU DX Coil EIR-FF,  !- Energy Input Ratio Function of Flow Fraction Curve Name
    118451 AHU DX Coil PLF,  !- Part Load Fraction Correlation Curve Name
    0,                       !- Nominal Time for Condensate Removal to Begin {s}
    0,                       !- Ratio of Initial Moisture Evaporation Rate and Steady State Latent Capacity {dimensionless}
    0,                       !- Maximum Cycling Rate {cycles/hr}
    0,                       !- Latent Capacity Time Constant {s}
    118451 AHU Cooling Coil Condenser Inlet,  !- Condenser Air Inlet Node Name
    AirCooled,               !- Condenser Type
    0,                       !- Evaporative Condenser Effectiveness {dimensionless}
    ,                        !- Evaporative Condenser Air Flow Rate {m3/s}
    0,                       !- Evaporative Condenser Pump Rated Power Consumption {W}
    0,                       !- Crankcase Heater Capacity {W}
    10;                      !- Maximum Outdoor Dry-Bulb Temperature for Crankcase Heater Operation {C}

! DOE-2.1E, COOL-CAP-FT for PTAC w/ SI temps

  Curve:Biquadratic,
    118451 AHU DX Coil Cap-FT,  !- Name
    0.942587793,             !- Coefficient1 Constant
    0.009543347,             !- Coefficient2 x
    0.00068377,              !- Coefficient3 x**2
    -0.011042676,            !- Coefficient4 y
    0.000005249,             !- Coefficient5 y**2
    -0.00000972,             !- Coefficient6 x*y
    12.77778,                !- Minimum Value of x
    23.88889,                !- Maximum Value of x
    18.0,                    !- Minimum Value of y
    46.11111;                !- Maximum Value of y

! DOE-2.1E, RATED-CCAP-FFLOW for PTAC

  Curve:Quadratic,
    118451 AHU DX Coil Cap-FF,  !- Name
    0.8,                     !- Coefficient1 Constant
    0.2,                     !- Coefficient2 x
    0,                       !- Coefficient3 x**2
    0.5,                     !- Minimum Value of x
    1.5;                     !- Maximum Value of x

! DOE-2.1E, COOL-EIR-FT for PTAC w/ SI temps

  Curve:Biquadratic,
    118451 AHU DX Coil EIR-FT,  !- Name
    0.342414409,             !- Coefficient1 Constant
    0.034885008,             !- Coefficient2 x
    -0.0006237,              !- Coefficient3 x**2
    0.004977216,             !- Coefficient4 y
    0.000437951,             !- Coefficient5 y**2
    -0.000728028,            !- Coefficient6 x*y
    12.77778,                !- Minimum Value of x
    23.88889,                !- Maximum Value of x
    18.0,                    !- Minimum Value of y
    46.11111;                !- Maximum Value of y

! DOE-2.1E, RATED-CEIR-FFLOW for PTAC

  Curve:Quadratic,
    118451 AHU DX Coil EIR-FF,  !- Name
    1.1552,                  !- Coefficient1 Constant
    -0.1808,                 !- Coefficient2 x
    0.0256,                  !- Coefficient3 x**2
    0.5,                     !- Minimum Value of x
    1.5;                     !- Maximum Value of x

! PLF = l.- Cd(1.-PLR) where Cd = 0.15

  Curve:Quadratic,
    118451 AHU DX Coil PLF,  !- Name
    0.85,                    !- Coefficient1 Constant
    0.15,                    !- Coefficient2 x
    0,                       !- Coefficient3 x**2
    0,                       !- Minimum Value of x
    1;                       !- Maximum Value of x



------------------------------------

Primary EnergyPlus support is found at:
http://energyplus.helpserve.com or send a message to energyplus-support@xxxxxxxx

The primary EnergyPlus web site is found at:
http://www.energyplus.gov

The group web site is:
http://groups.yahoo.com/group/EnergyPlus_Support/

Attachments are currently allowed but be mindful that not everyone has a high speed connection.  Limit attachments to small files.

EnergyPlus Documentation is searchable.  Open EPlusMainMenu.pdf under the Documentation link and press the "search" button.
Yahoo! Groups Links

<*> To visit your group on the web, go to:
    http://groups.yahoo.com/group/EnergyPlus_Support/

<*> Your email settings:
    Individual Email | Traditional

<*> To change settings online go to:
    http://groups.yahoo.com/group/EnergyPlus_Support/join
    (Yahoo! ID required)

<*> To change settings via email:
    EnergyPlus_Support-digest@xxxxxxxxxxxxxxx 
    EnergyPlus_Support-fullfeatured@xxxxxxxxxxxxxxx

<*> To unsubscribe from this group, send an email to:
    EnergyPlus_Support-unsubscribe@xxxxxxxxxxxxxxx

<*> Your use of Yahoo! Groups is subject to:
    http://docs.yahoo.com/info/terms/